High-low pressure pump



March 7, 1967 LAUCK 3,307,482

HIGHLOW PRESSURE PUMP Fil ed Dec. 22, 1964 2 Sheets-Sheet 1 INVENTOR JOHN A. LAUCK Ailing d ATTORNYS March 7, 1967 J. A. LAUCK 3,307,482

HIGH-LOW PRESSURE PUMP Filed Dec. 22, 1964 2 SheetsSheet 2 INVENTOR JOHN .4. LAUCK United States Patent O 3,307,482 HIGH-LOW PRESSURE PUMP John A. Lauck, Benton Harbor, Mich., assignor to Hydromotive, Inc, Cleveland, Ohio, a corporation of Ohio Filed Dec. 22, 1964, Ser. No. 420,258 Claims. (Cl. 103-37) This invention relates generally, as indicate-d, to .a highlow pressure pump and, more particularly, to a hand pump which is adapted to provide high rates of flow at low pressures, and low rates of flow at high pressures.

One or more hydraulic hand pumps especially of the fixed displacement type, are used by almost all service garages and construction firms for actuating jacks and the like, and. most manufacturing plants have several of these pumps for the hydrostatic testing of hydraulic cylinders, valves, and other component parts of a hydraulic system. The major objection to the use of such pumps is that their displacement rate is usually so small that they are very ineflicient, particularly at low pressures when very little force is required to operate them. While it is true that the efiiciency of the pump at low pressures could easily be improved simply by increasing the pump displacement, if this were done, then the pump could not be used at high pressures since an undue amount of force would be required to displace this large volume of fluid at such high pressures. One way of solving this problem is to provide a variable volume pump capable of delivering a high volume of fluid at low pressures, but only a low volume of fluid at high pressures, which is the principal aim of this invention. In this way, it is possible to deliver from the pump as much hydraulic fluid as is generally possible for a given amount of work input, regardless of the pressure at which such fluid is being supplied by the pump.

Although variable displacement pumps are not new, none of those which are presently available are as efficient, inexpensive, or simple in construction and operation as is the pump of this invention. In general, the pump disclosed herein consists of a high and low volume pump assembly, both of which are operative simultaneously to pump a high volume of fluid at low pressures, but only the low volume pump assembly is operative to pump fluid at high pressures. Removal of the high volume, low pressure pump assembly at high pressures is effected by movement of a shuttle valve to a position communicating the high volume, low pressure assembly with a reservoir when the pressure in the system reaches a predetermined, value. To prime the low volume pump assembly, there is provided a check valve in a passagew-ay interconnecting the large volume and low volume pump assemblies which permits fluid to pass through the passageway from the large volume pump to the low volume pump on the first downward stroke of the operating handle.

Accordingly, it is another object of this invention to provide a novel high-low pressure pump as discussed above which uses two separate pump assemblies, both of which are adapted to pump fluid at low pressures through actuation of a single operating handle, but only one of which is adapted to pump fluid at high pressures.

Still another object is to provide such a pump with a shuttle valve which is adapted to remove the high volume, low pressure pump assembly from the system when the output pressure reaches a predetermined value.

Yet another object is to provide such a pump with a shuttle valve of the type described above which is balanced by the pressure from the large volume pump assembly so that there are no reactionary forces to overcome before the high volume pump assembly will operate at low pressures,

3,307,482 Patented Mar. 7, 1967 A further object is to provide such a pump with a novel means for priming the low volume pump assembly, including a check valve in a passage interconnecting the large volume and low volume pump assemblies which permits fluid to pass through the passage from the large volume pump to the low volume pump on the first downward stroke of the operating handle.

Another object is to provide a variety of different sizes of pistons and gland. assemblies for such a pump both to vary its displacement per stroke and the maximum pressure at which the pump can operate with reasonable handle loads.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully discussed and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which he principle of the invention may be employed.

In said annexed drawing:

FIG. 1 is an isometric view of the preferred form of hydraulic hand pump constructed in accordance with the present invention;

FIG. 2 is an enlarged vertical section of the pump of FIG. 1 taken on the plane of the line 22 thereof;

FIG. 3 is .a vertical section taken on the plane of the line 3-3 of FIG. 2; and

FIG. 4 is an enlarged vertical section through a portion of the pump housing taken on the plane of the line 44 of FIG. 3.

Referring now to the drawing, and first of all to FIGS. 1 and 2 thereof, the preferred form of high-low pressure pump of the present invention is generally indicated at 1 and comprises a unitary cast housing 2 which is provided with a pair of laterally spaced pumping cylinders or chambers 3 and 4 which slidably receive pistons 5 and 6, respectively. One of the pumping chambers 3 has a much larger capacity than the other pumping chamber 4 and defines with the larger piston 5 disposed therein a high volume pump assembly 7. The pumping chamber 4, on the other hand, being smaller than the pumping chamber 3 as aforesaid, defines with the piston 6 a small volume pump assembly 8.

As perhaps best seen in FIG. 2, the pistons 5 and 6 are guided in their respective pumping chambers 3 and 4 by means of gland assemblies 11 and 12 which threadedly engage counterbores 13 and 14 in the open ends of the pumping chambers, such gland assemblies being provided with seals to prevent leakage of fluidfrom the chambers. To effect reciprocating movement of the pistons 5 and 6 in their respective pumping chambers 3 and 4, an operating handle 15 is used. Preferably, one end 16 of the handle 15 is pivotally connected to an upstanding projection 17 of the housing 2 for pivotal movement of the handle toward and away from the pumping chambers 3 and 4, and the pistons 5 and 6 are connected to the operating handle 15 between the ends thereof. This connection between the operating handle 15 and pistons 5 and 6 is of the lost motion type, consisting of two pins 19 and 20 which extend between the laterally spaced apart arms 21 of the operating handle 15 and through horizontally extending slots 22 and 23 in extensions 24 and 25 of the pistons positioned between such arms 21. Accordingly, only vertical movement of the pistons 5 and 6 in their respective pumping chambers 3 and 4 is permitted during pivotal movement of the handle 15. Thus, when the handle 15 is raised, the pistons 5 and 6 are moved upwardly, with any horizontal movement of the pins 23 and 24 being taken care of by the slots 21 and 22. Of course, when the pins 23 and 24 engage the left ends of the slots 21 and 22, further upward movement of the handle 15 and pistons and 6 is precluded. Conversely, when the handle is lowered, the pistons 5 and 6 are moved downwardly in their respective pumping chambers 3 and 4 with the pin and slot connections between the pistons and operating handle again taking care of any horizontal movement of the operating handle during such downward movement. As evident, the larger piston S is further removed from the pivot point 26 of the operating handle 15 than the smaller piston 6. Therefore, the piston 5 will move a greater distance in its pumping chamber than will the piston 6 upon movement of the operating handle 15, thereby further increasing its displacement over the displacement of the smaller piston.

As clearly shown in FIG. 3, a reservoir 28 which is adapted to be filled with hydraulic fluid of any well known type through aplugged opening 29 or the like is secured to one side of the pump housing 2 as by means of a tie rod 31 and nut 32. To preclude leakage of such hydraulic fluid from the reservoir 28, there is provided a gasket 33 between the mating surfaces of the pump housing 2 and the reservoir 28. While the capacity of the reservoir 28 may obviously be varied as desired, depending upon the amount of fluid needed to operate a particular piece of equipment, it has been found that by making available one, two, and three quart capacity reservoirs, almost every need can be taken care of.

Extending outwardly from this same side of the pump housing 2 into the interior of the reservoir 28 there is a projection 34 which, as clearly shown in FIG. 4, includes a horizontally extending body portion 35 and a pair of depending, laterally spaced extensions 36 and 37. The extension 36 has a substantially vertically extending passageway 38 which communicates the interior of the reservoir 28 adjacent the bottom thereof with the high volume pumping chamber 3 via a horizontal passageway 39 and a vertical passageway 46. Moreover, the lower end of the passageway 38 is counterbored for receipt of a combination seat and seat retainer 41 against which a spring biased check valve 42 is adapted to be seated when the pressure in chamber 3 is greater than the pressure in reservoir 28 to prevent return flow of fluid.

The extension 37 is also provided with a substantially vertically extending passageway 43 therein, but which communicates the reservoir 28 with the smaller pumping chamber 4 via a horizontal passageway 44 and a vertical passageway 45. Also, the lower end of the passageway 43 is counterbored for receipt of a combination seat and seat retainer 46 which, like the combination seat and seat retainer 41 in the passageway 38, is engaged by a spring biased check valve 47 when the pressure in the small pumping chamber 4 is greater than the pressure in the reservoir 28.

Within the horizontally extending portion 35 of the projection 34 there is a horizontal passageway 48 which interconnects the high and low volume pump assemblies 7 and 8, respectively, via passageways 39, 4t), 44, and 45. However, fluid is permitted to flow only from the high volume pump assembly 7 to the low volume pump assembly 8 as by disposing a check valve 49 in the passageway 48; and not from the low volume pump assembly 8 to the high volume pump assembly 7, for a purpose which will be subsequently more fully explained.

Referring again to FIG. 2, the passageways 40 and 45 communicate directly with the bottom of their respective pumping chambers 3 and 4 and extend downwardly therefrom into a common high pressure passage 52 into which fluid under pressure is pumped by the pump assemblies 7 and 8 during the downward stroke of the operating handle 15. To prevent back flow of fluid from the high pressure passage 52 to the pumping chambers 3 and 4, high pressure check valves 53 and 54 are disposed in the high pressure passage 52 for yieldable engagement against cult to pump the operating handle 15.

seats 55 and 56 inserted in the adjacent ends of the passageways 40 and 45, such check valves 53 and 54 being maintained in alignment with their respective seats 55 and 56 by retainers 57 and 58 threadedly engaging apertures in the bottom wall of the pump housing 2.

The open end 60 of the high pressure passage 52 is preferably threaded to permit attachment of a flexible hose or the like (not shown) which may be used to communicate the pump 1 either directly to a hydraulic jack for actuation thereof or to a pressure accumulator tank for storage of the high pressure fluid produced by the pump 1.

As evident, both the high volume pump assembly 7 and the low volume pump assembly 8 of the pump 1 as thus far described are effective upon raising and lowering the operating handle 15 to pump fluid into the high pressure passage 52 via passageways 40 and 45 and out through the open end 60. Moreover, since the displace ment of the high volume pump assembly 7 is relatively high, say about 2.75 cubic inches per stroke, a jack or the like connected to the pump 1 can be actuated quite quickly with very little effort, especially at low pressures.

However, because the displacement rate is quite high, as the pressure increases, it will become increasingly diffi- It may become so difficult, in fact, that if some means is not provided for lowering the amount of fluid displaced during each downward stroke of the operating handle, it will become impossible or at least extremely difficult to operate the pump 1 at high pressures. Accordingly, when the pressure reaches somewhere between 80 and 100 p.s.i., but not before, it is desired that the high volume pump assembly 7 be automatically removed from the system, thereby leaving only the low volume pump assembly 8 which has a capacity of say .2 cubic inch per stroke so that pressures of up to 5000 psi. can be obtained with reasonable handle loads. To accomplish this, a shuttle valve is slidably disposed in a transverse bore 66 in the housing 2 which intersects the passageway 40 between the large pumping chamber 3 and high pressure passage 52. The shuttle valve 65 consists of a pair of longitudinally spaced lands 67 and 68 the diameter of which are substantially the same as the diameter of the bore 66 to form a fluid-tight seal therebetween, such lands 67 and 68 being spaced apart a distance greater than the diameter of the passageway 40 so that when the shuttle valve 65 is yieldably urged to the right in the bore 66 as viewed in FIG. 2 by the compression spring 69, fluid will be permitted to flow freely from the pumping chamber 3 through the passageway 40 about the reduced mid-portion 70 of the shuttle valve 65 to the high pressure passage 52. Also, when the shuttle valve 65 is in the extreme right position shown, fluid communication between the passageway 40 and a return passage 71, which communicates the 'bore 66 with the reservoir 28, is blocked by the land 68.

Because the lands 67 and 68 of the shuttle valve 65 are always on opposite sides of the passageway 40, the fluid pressure in passageway 40 will not cause movement of the shuttle valve 65 in either direction. Thus, the shuttle valve 65 is balanced at its mid-section and there are no reactionary forces thereat which must first be overcome before the high volume pump assembly 7 is effective in pumping fluid into the high pressure passage 52. Accordingly, at low pressures the fluid pumped by the high volume pump assembly 7 is permitted to pass through the passage 40 into the high pressure passage 52 without obstruction. However, there is a passageway in the pump housing 2 communicating the high pressure passage 52 with the extreme right end of the bore 66. Accordingly,

. tive to resist this'leftward movement of the shuttle valve 65 is the bias of the spring 69. Once this is overcome, the shuttle valve 65 will slide to the left, moving land 68 past the return passage 71 and thereby permitting the fluid being pumped by the high volume pump assembly 7 to flow back to the reservoir 28 through such return passage at little or no pressure. As previously indicated, it is preferred that this leftward movement of the shuttle valve 65 occur when the pressure in the high pressure passage 52 reaches 80 to 100 p.s.i., since if the high volume pump assembly 7 is retained in the system above this pressure level, too much effort is required further to operate the handle 15.

Adjacent the left end of the bore 66 there is provided a bleed hole 76 which leads to the reservoir 28 to permit the escape of any oil which might otherwise become trapped between the left end of the bore 66 and shuttle valve 65. Also, the pump 1 may be mounted on a suitable support stand 80 (FIG. 1) if desired as by means of nut and bolt assemblies 82 inserted through mounting holes 83 in the base of the pump housing 2.

In theory at least, when the operating handle 15 is raised, a vacuum is created in the pumping chambers 3 and 4, thereby causing valve checks 42 and 47 to open and permitting oil to pass from the reservoir 28 to the pumping chambers 3 and 4 via their respective passageways. Then, as the handle is depressed, the pistons 5 and 6 will displace the fluid in the chambers 3 and 4, causing it to flow through the passageways 40 and 45 into the high pressure passage 52. However, in actual practice it has been found that the vacuum created in the small chamber 4 during the upward stroke of the operating handle 15 is generally not sufficient to draw fluid into the same, at least not on the first stroke. The large piston 5, however, having a much greater displacement, is able to prime itself on the first upward stroke. Therefore, on the first compression stroke, the large volume pump assembly 7 actually pumps fluid, but not the small pump assembly 8. Nor does the small pump assembly 8 pump fluid on subsequent strokes of the operating handle, the reason being that the fluid which was pumped by the high volume pump assembly 7 on the first stroke builds up pressure against the high pressure check valve 54 to such an extent that the small piston 4 cannot purge itself of air and thus will not prime itself no matter how many strokes are made.

To overcome this priming difficulty of the smaller chamber 4, the passageway 48 is provided in the horizontally extending portion 35 of the projection 34 with the check valve 49 disposed therein as aforesaid to communicate the smaller chamber 4 with the larger chamber 3. Accordingly, a portion of the fluid which is pumped by the high volume pump assembly 7 during the first downward stroke of the operating handle 15 is directed through the passageway 4-8 and check valve 49 into the smaller chamber 4 of the low volume pump assembly 8, thus pressurizing the same and reducing its clearance volume to zero. The smaller pumping chamber 4 now being primed, it will then operate satisfactorily on the subsequent strokes of the operating handle 15. Of course, the spring 84 which yieldably urges the check valve 49 to its seated position must be weaker than the spring 85 which urges the check valve 53 to its seated position, or otherwise all of this fluid would flow into the high pressure passage 52.

Although the displacements of the high volume pump assembly 7 and low volume pump assembly 8 need not be of any particular amount, it has been found that the pump 1 is ideally suited for fast operation of jacks, cylinders, presses, and the like if the displacement of the large piston 5 is approximately 2.75 cubic inches per stroke and the displacement of the small piston 6 is approximately .2 cubic inches per stroke. Also, it is preferred that the high volume pump assembly 7 be unloaded directly to the reservoir 28 in the manner previously discussed when the pressure in the high pressure passage 52 reaches somewhere between 80 and 100 p.s.i.

With the pump 1 constructed as described above, it is capable of producing pressures of up to 5000 p.s.i. with reasonable handle loads. However, another important feature of this invention is that the pistons 5 and 6 and their respective gland assemblies 11 and 12 can readily be replaced with pistons and gland assemblies of different sizes so that the same pump 1 can be modified to operate at pressures of 10,000 p.s.i. or even higher with reasonable handle loads. Moreover, the hand pump 1 can be supplied individually or in combination with a hydraulic cylinder to form a jack in capacities of 5, 10, 25, and 50 ton, or the jack may be used in combination with a stand to form a hydraulic press in capacities of 5, 10, and 25 ton.

While it is not absolutely necessary, it is desirable that the pump 1 also be provided with a return passage 86 communicating the high pressure passage 52 with the reservoir 28 and that a manually controlled ball valve 87 be disposed in the high pressure passage 52 adjacent the return passage 86 for opening and closing of such passage to relieve the pressure in the high pressure passage 52 when desired. This may be accomplished simply by screwing or unscrewing a valve stem 88 into or out of the pump housing 2 through rotation of a control knob 89 in the desired direction, such valve stem 88 being provided with a socket 90 at its inner end for securely holding the ball valve 87. Note, in particular, FIG. 3 in this respect.

From the above discussion, it should now be readily apparent that the pump of the present invention is extremely efiicient in that it is operative automatically to pump a high volume of fluid at low pressures and a low volume of fluid at high pressures. This is accomplished by removing from the system the larger of two pump assemblies when the pressure in the system reaches a predetermined value. Moreover, a novel means is provided for priming the low volume pump assembly to assure that it operates satisfactorily at least on the second stroke of the operating handle.

Other modes of applying the principles of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore, particularly point out and distinctly claim as my invention:

1. A high-low pressure pump comprising a pair of pump assemblies, the displacement of one of said pump assemblies being much larger than the displacement of the other, each of said pump assemblies including a pumping chamber and a piston slidably received therein, a fluid reservoir, first and second passageways communicating each of said chambers with said reservoir, check valves in said first and second passageways for permitting fluid to flow therethrou-gh only in the direction of said pumping chambers, a high pressure outlet passage, third and fourth passageways communicating said chambers directly with said high pressure outlet passage, additional check valves in said third and fourth passageways for permitting fluid to flow from said pumping chambers only in the direction of said high pressure outlet passage, means operatively connected to said pistons for reciprocating the same, a fifth passageway interconnecting said chambers, and another check valve in said fifth passageway operative to permit a portion of the fluid pumped by said chamber for the larger displacement pump assembly on the first pumping stroke of its piston to enter said chamber for the smaller displacement pump assembly to prime the same, thus insuring satisfactory operation of said smaller displacement pump assembly after such first pumping stroke.

2. The pump of claim 1, further comprising means in said housing operative to communicate the chamber for said larger displacement pump assembly directly with said reservoir when the pressure in said high pressure outlet passage reaches a preselected value to permit pressures above such preselected value to be developed by said smaller displacement pump assembly only.

3. The pump of claim 1, wherein said pistons are guided in said pump chambers by gland assemblies threadedly engaging counterbores in the outer ends of said chambers, said gland assemblies and pistons being adapted to be replaced with gland assemblies and pistons of different sizes for varying the maximum amount of pressure that may be developed by said pump.

4. The pump of claim 1, wherein said means for reciprocating said pistons comprises a handle pivotally connected to said housing, extensions on said pistons having horizontal slots therein, and pins projecting from said handle through said slots, the length of said slots being such that said pins will engage the ends of said slots when the maximum desired outward movement of said handle and pistons is reached.

5. A hydraulic pump of the type which is adapted to deliver a high volume of fluid at low pressures and a low volume of fluid at high pressures, comprising a housing, high and low volume pump assemblies in said housing, each including a pumping chamber and a piston reciprocably mounted in said pumping chambers, means for reciprocating said pistons, a fluid reservoir, means communicating said fluid reservoir with said pumping chambers to permit flow of fluid from said reservoir in the direction of said pumping chambers and prevent flow of fluid in the opposite direction, a high pressure outlet passage in said housing, first and second passageways communicating said pumping chambers for said high and low volume pump assemblies, respectively, with said high pressure outlet passage, means disposed in said first and second passageways to permit flow of fluid therethrough from said pumping chambers to said high pressure outlet passage and prevent flow of fluid in the opposite direction, and means for unloading the pumping chamber for said high volume pump assembly to said reservoir in response to a predetermined pressure in said high pressure outlet passage to permit additional buildup of pressure substantially higher than such predetermined pressure by said low volume pump assembly only, said last-mentioned passage, said shuttle valve means comprising a spool valve having a pair of lands disposed on either side of said first passageway to neutralize the effect of the pressure in said pumping chamber for said high volume pump assembly on said shuttle valve means, a return passage in said housing communicating said bore with said reservoir, another passageway in said housing communicating one end of said bore with said high pressure outlet passage to permit the pressure in said high pressure outlet passage to act on said shuttle valve means tending to urge the same into a position whereat fluid communication is established between said first passageway and said return passage, and spring means for urging said shuttle valve means to a position whereat fluid communication between said first passageway and said return passage is blocked, said spring means being suflicient to overcome the force exerted against said shuttle valve means by such high pressure only when such high pressure is below such predetermined value.

References Cited by the Examiner UNITED STATES PATENTS 1,589,333 6/1926 Dornenburg -52 2,081,221 5/1937 Coberly 103-169 2,250,551 7/ 1941 Pfauser 103-37 2,372,375 3/ 1945 Groves 103-37 2,442,058 5/1948 Page 103-37 2,447,650 8/ 1948 Haumerson 60-52 2,495,319 1/1950 Ferris 60-52 2,659,307 11/1953 Framheim 103-11 2,820,415 1/1958 Born 103-37 2,913,985 11/ 1959 Harrison 103-37 LAURENCE V. EFNER, Primary Examiner. 

1. A HIGH-LOW PRESSURE PUMP COMPRISING A PAIR OF PUMP ASSEMBLIES, THE DISPLACEMENT OF ONE OF SAID PUMP ASSEMBLIES BEING MUCH LARGER THAN THE DISPLACEMENT OF THE OTHER, EACH OF SAID PUMP ASSEMBLIES INCLUDING A PUMPING CHAMBER AND A PISTON SLIDABLY RECEIVED THEREIN, A FLUID RESERVOIR, FIRST AND SECOND PASSAGEWAYS COMMUNICATING EACH OF SAID CHAMBERS WITH SAID RESERVOIR, CHECK VALVES IN SAID FIRST AND SECOND PASSAGEWAYS FOR PERMITTING FLUID TO FLOW THERETHROUGH ONLY IN THE DIRECTION OF SAID PUMPING CHAMBERS, A HIGH PRESSURE OUTLET PASSAGE, THIRD AND FOURTH PASSAGEWAYS COMMUNICATING SAID CHAMBERS DIRECTLY WITH SAID HIGH PRESSURE OUTLET PASSAGE, ADDITIONAL CHECK VALVES IN SAID THIRD AND FOURTH PASSAGEWAYS FOR PERMITTING FLUID TO FLOW FROM SAID PUMPING CHAMBERS ONLY IN THE DIRECTION OF SAID HIGH PRESSURE OUTLET PASSAGE, MEANS OPERATIVELY CONNECTED TO SAID PISTONS FOR RECIPROCATING THE SAME, A FIFTH PASSAGEWAY INTERCONNECTING SAID CHAMBERS, AND ANOTHER CHECK VALVE IN SAID FIFTH PASSAGEWAY OPERATIVE TO PERMIT A PORTION OF THE FLUID PUMPED BY SAID CHAMBER FOR THE LARGER DISPLACEMENT PUMP ASSEMBLY ON THE FIRST PUMPING STROKE OF ITS PISTON TO ENTER SAID CHAMBER FOR THE SMALLER DISPLACEMENT PUMP ASSEMBLY TO PRIME THE SAME, THUS INSURING SATISFACTORY OPERATION OF SAID SMALLER DISPLACEMENT PUMP ASSEMBLY AFTER SUCH FIRST PUMPING STROKE. 